body{
 background-image: url(../img/back.jpg);
 background-repeat: no-repeat;
    background-size: cover;
    background-attachment: fixed;
    opacity: 0.7;

}
#top li{
    width:300px;
    /* height: 33px; */
    float: left;
    text-align: center;
    margin-top: 25px;

}
#top a{
    color: black;
}
#content{
    width: 600px;
    height: 1500px;
   
    
}

